Updated to Game Version 2.34.0, Asset Version 451 (January 31st, 2024).
Summer's Van is a repeating event in Pocket Mortys that always occurs the week after a Raid event. Her van is located in the dimension listed in the "Location" column of the table (and can also be accessed via the poo emoji when the event is active). Purchasing the Pack for x15 coupons or any of the items listed in the "Items" column of the table will allow you to battle Summer. If you defeat her, you will be given one of the Mortys listed in the "Morty Rewards" column, with a high chance of a shiny Morty. Summer will use the Mortys listed in the "Summer's Mortys" column when battling.